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most of what we do and think and feel is not under our conscious control.
Our brains run mostly on autopilot, and the conscious mind has little access to the giant and mysterious factory that runs below it.
When an idea is served up from behind the scenes, your neural circuitry has been working on it for hours or days or years, consolidating information and trying out new combinations.
Consider what happens when you move your arm. Your brain depends on thousands of nerve fibers registering states of contraction and stretching—and yet you perceive no hint of that lightning storm of neural activity.
In other words, the storm of nerve and muscle activity is registered by the brain, but what is served up to your awareness is something quite different.
consciousness is a way of projecting all the activity in your nervous system into a simpler form. The billions of specialized mechanisms operate below the radar—some collecting sensory data, some sending out motor programs, and the majority doing the main tasks of the neural workforce: combining information, making predictions about what is coming next, making decisions about what to do now.
may come as a surprise that about one-third of the human brain is devoted to vision.
The brain doesn’t need a full model of the world because it merely needs to figure out, on the fly, where to look, and when.10
Your internal model has some general idea that you’re in a coffee shop, that there are people to your left, a wall to your right, and that there are several items on the table. When your partner asks, “How many lumps of sugar are left?” your attentional systems interrogate the details of the bowl, assimilating new data into your internal model. Even though the sugar bowl has been in your visual field the entire time, there was no real detail there for your brain. It needed to do extra work to fill in the finer points of the picture.
You can know some things about a scene without knowing other aspects of it, and you become aware of what you’re missing only when you’re asked the question.
The brain generally does not need to know most things; it merely knows how to go out and retrieve the data. It computes on a need-to-know basis.
we are not conscious of much of anything until we ask ourselves about it.
You’re not perceiving what’s out there. You’re perceiving whatever your brain tells you.
the difference between being awake and being asleep is merely that the data coming in from the eyes anchors the perception. Asleep vision (dreaming) is perception that is not tied down to anything in the real world; waking perception is something like dreaming with a little more commitment to what’s in front of you.
The cortex sends its predictions to the thalamus, which reports on the difference between what comes in through the eyes and what was already anticipated. The thalamus sends back to the cortex only that difference information—that is, the bit that wasn’t predicted away. This unpredicted information adjusts the internal model so there will be less of a mismatch in the future. In this way, the brain refines its model of the world by paying attention to its mistakes.
perception reflects the active comparison of sensory inputs with internal predictions.
awareness of your surroundings occurs only when sensory inputs violate expectations.
The best way to calibrate timing expectations of incoming signals is to interact with the world: each time a person kicks or knocks on something, the brain can make the assumption that the sound, sight, and touch should be simultaneous. If one of the signals arrives with a delay, the brain adjusts its expectations to make it seem as though both events happened closer in time.
procedural memory, and it is a type of implicit memory—meaning that your brain holds knowledge of something that your mind cannot explicitly access.2
This is what consciousness does: it sets the goals, and the rest of the system learns how to meet them.
Brains are like representative democracies.7
They are built of multiple, overlapping experts who weigh in and compete over different choices.
In a single cubic millimeter of brain tissue, there are some one hundred million synaptic connections between neurons.
We then learned that the way we see the world is not necessarily what’s out there: vision is a construction of the brain, and its only job is to generate a useful narrative at our scales of interactions
If our brains were simple enough to be understood, we wouldn’t be smart enough to understand them.
